1. Field of the Invention
The present invention relates to a sputtering apparatus and a sputtering method.
2. Description of the Related Art
Sputtering is a technology in which a substrate and a target (a member to become the raw material of a sputtering film) are arranged in vacuum, and plasma is generated in the vacuum and a film is formed on the substrate. According to the sputtering using plasma, because sputtered particles of high energy reach the substrate, adhesion of the sputtered particles with the substrate becomes high. Therefore, the sputtering using plasma has an advantage that a precise film can be formed, and is used in the mass production of many products such as electronic components and optical thin films and the like.
Further, in a magnetron sputtering among sputterings, a magnetic circuit is placed in the back surface of a target and a magnetic tunnel is formed on the target surface. By trapping electrons by this line of magnetic force, ionization rate increases, high-density plasma is generated, and the film-forming speed can be increased. Therefore, the industrial use of the magnetron sputtering has been progressed rapidly.
However, in the magnetron sputtering, since a magnetic tunnel is localized on a small part on the target, plasma is localized, and a small part of the target is selectively eroded. In practice, only approximately 10 to 20% of the target is emitted by the sputtering. In order to solve this problem, there are proposed methods including a method to increase the use efficiency of the target by rotating a magnet arranged at the back surface of the target, a method to move a plasma generation region in time by oscillating a magnet arranged at the back surface of the target, a method to move plasma by an electromagnet or the like, and others. However, in these methods, since a moving unit is required to be added to a sputtering apparatus, a mechanism of the apparatus tends to become complicated and equipment costs also tend to become high.
On the other hand, a method is proposed in which as a measure to generate plasma in a wide region near the surface of the target while fixing the magnet arranged on the back surface of the target, “a magnetic circuit that is composed of a combination of a magnet magnetized perpendicularly to the target surface and a magnet magnetized in parallel thereto” is arranged on the back surface of the target (refer to Japanese Patent Application Laid-Open No. H07-507360, Japanese Patent Application Laid-Open No. H11-500490, and the U.S. Pat. No. 4,964,968).